I´ve the same problem. I´ve tried to follow your steps.
and I get this message ‘Advanced Custom Fields v3.0.0 requires a database upgrade.’
i press button
Migrating Location Rules…
Migrating Fields… (is stopped in this step)
if I refresh the browser i receive the same message again
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users